Medical device delivery

Abstract

A stent delivery system includes a core member and an expandable member coupled to the core member distal segment. A stent extends along the core member distal segment such that an inner surface of the stent is positioned over the expandable member. The stent has a primary heat-set configuration where the stent is radially expanded, and a secondary heat-set configuration where the stent is radially compressed. The expandable member is adapted to radially expand at least a portion of the stent from a radially compressed configuration toward a radially expanded configuration.

The invention claimed is: 
     
       1. A stent delivery system, comprising:
 a core member configured for advancement within a corporeal lumen; 
 an expandable member positioned on the core member such that a first end is secured to the core member and a second end is slidingly coupled to the core member, wherein the expandable member is adapted to be radially expanded from a collapsed delivery configuration to an expanded configuration; 
 an actuator coupled to the expandable member second end and configured such that movement of the actuator selectively expands the expandable member from the collapsed delivery configuration to the expanded configuration, wherein movement of the actuator in a first direction moves the second end toward the first end, thereby causing the expandable member to shorten and radially expand, and wherein relative movement of the actuator in a second direction moves the second end away from the first end, thereby causing the expandable member to lengthen and radially compress; 
 a stent extending along the core member and over the expandable member, the stent having a primary set configuration with a radially expanded state and a secondary set configuration with a radially low-profile state, the stent assuming a stent delivery configuration in which the stent is more strongly biased towards the secondary set configuration such that the stent is radially compressed against the core member until expanded via the expandable member, and wherein the stent is configured such that, after the underlying expandable member expands the stent, the stent is more strongly biased towards the primary set configuration such that the stent continues to expand after the expandable member has finished expanding until the stent assumes a stent expanded configuration in which the stent is radially expanded from the stent delivery configuration, wherein the stent expanded configuration has a greater radial dimension than the expandable member expanded configuration; and 
 a proximal coupling assembly disposed over the core member and underlying a proximal portion of the stent, the proximal coupling assembly positioned proximal to the expandable member, wherein the proximal coupling assembly comprises one or more stent engagement members configured to engage an inner wall of the stent against an overlying catheter, 
 wherein, in the collapsed delivery configuration, the expandable member underlies the stent along less than half the entire length of the stent. 
 
     
     
       2. The system of  claim 1 , wherein the expandable member comprises a main body having a cylindrical shape when the expandable member is in the collapsed delivery configuration. 
     
     
       3. The system of  claim 1 , wherein, in the expanded configuration, the expandable member contacts the stent along less than half of the entire length of the stent. 
     
     
       4. The system of  claim 1 , further comprising a catheter through which the core member and stent are configured to be slidably advanced. 
     
     
       5. The system of  claim 1 , wherein the stent is formed from a shape memory material. 
     
     
       6. The system of  claim 1 , wherein the stent is heat-set into the primary set configuration. 
     
     
       7. The system of  claim 1 , wherein the stent is heat-set into the secondary set configuration. 
     
     
       8. The system of  claim 1 , wherein the proximal coupling assembly is configured to enable resheathing of the stent within the overlying catheter after a distal portion of the stent has been expanded via the expandable member. 
     
     
       9. A stent delivery system, comprising:
 a core member configured for advancement within a corporeal lumen; 
 an expandable member coupled to the core member, the expandable member having a first end and a second end; 
 an actuator coupled to the expandable member and configured such that (1) movement of the actuator in a first direction causes the first end and second end of the expandable member to be moved closer together, thereby expanding the expandable member, and (2) movement of the actuator in a second direction causes the first end and second end of the expandable member to move further apart, thereby collapsing the expandable member; 
 a stent extending along the core member and over the expandable member, the stent comprising a memory material, the stent further comprising a stent delivery configuration wherein the stent is radially compressed against the core member and comprises a maximum stent delivery diameter, wherein the stent is characterized by the memory material having a secondary set configuration wherein the stent is radially compressed and comprises a secondary stent maximum diameter which is no greater than the maximum stent delivery diameter, and wherein the stent is further characterized by the memory material having a primary set configuration wherein the stent is radially expanded and comprises a primary set maximum diameter which is greater than the maximum stent delivery diameter; and 
 a proximal coupling assembly disposed over the core member and underlying a proximal portion of the stent, the proximal coupling assembly positioned proximal to the expandable member, wherein the proximal coupling assembly comprises one or more stent engagement members configured to engage an inner wall of the stent against an overlying catheter, 
 wherein, in the stent delivery configuration, the expandable member underlies the stent along less than half the entire length of the stent, and 
 wherein, when the stent is in the stent delivery configuration, the stent is more strongly biased towards the second set configuration, and wherein, after the underlying expandable member expands the stent, the stent is more strongly biased towards the primary set configuration such that the stent continues to expand after the expandable member has finished expanding. 
 
     
     
       10. The stent delivery system of  claim 9 , wherein the stent is adapted to be deployed within a body lumen, wherein the stent after deployment in the body lumen comprises a stent expanded configuration wherein the stent is radially expanded against a wall of the body lumen and wherein the stent comprises a maximum stent expanded diameter which is no greater than the primary set maximum diameter. 
     
     
       11. The system of  claim 9 , wherein the stent is formed from a shape memory material. 
     
     
       12. The system of  claim 9 , wherein the stent is heat-set into the primary set configuration. 
     
     
       13. The system of  claim 9 , wherein the stent is heat-set into the secondary set configuration. 
     
     
       14. The system of  claim 9 , wherein the expandable member is adapted to be selectively radially expanded from a collapsed delivery configuration to an expanded deployment configuration. 
     
     
       15. A stent delivery system, comprising:
 a core member configured for advancement within a corporeal lumen;
 an expandable member coupled to the core member, the expandable member having a first end and a second end; an actuator coupled to the expandable member and configured such that (1) movement of the actuator in a first direction causes the first end and second end of the expandable member to be moved closer together, thereby expanding the expandable member, and (2) movement of the actuator in a second direction causes the first end and second end of the expandable member to move further apart, thereby collapsing the expandable member; and 
 
 a stent extending along the core member and over the expandable member, the stent comprising a memory material having a primary set configuration in which the stent is radially expanded and a secondary set configuration in which the stent is radially collapsed, wherein the stent is configured to maintain the secondary set configuration until the expandable member expands against the stent to urge the stent radially outwardly to a first expanded state, and wherein the stent is configured to continue expanding after the expandable member has finished expanding such that the stent assumes a second, larger expanded state, wherein in the secondary set configuration, the expandable member underlies the stent along less than half the entire length of the stent; and 
 a proximal coupling assembly disposed over the core member and underlying a proximal portion of the stent, the proximal coupling assembly positioned proximal to the expandable member, wherein the proximal coupling assembly comprises one or more stent engagement members configured to engage an inner wall of the stent against an overlying catheter. 
 
     
     
       16. The stent delivery system of  claim 15 , wherein in the secondary set configuration, the stent is biased towards a collapsed configuration in which a radially outermost dimension of the stent is less than a radially outermost dimension of the core member. 
     
     
       17. The stent delivery system of  claim 15 , wherein in the primary set configuration, the stent is biased towards an expanded configuration in which a radially outermost dimension of the stent is greater than an outermost dimension of the expandable member in an expanded state. 
     
     
       18. The stent delivery system of  claim 15 , wherein the actuator comprises a pull wire. 
     
     
       19. The stent delivery system of  claim 15 , wherein the expandable member comprises at least one of: a braid, a mesh, a slotted hypotube, or a coil.